Filling mold



A. KADOW April 15, 1930.

April 15, 1930. A. KADow 1,754,469

FILLINGI MoLD Filed June 19 1926 I 2 Sheets-Sheet 2 auot m4; S

Paienied Apr. is, 1930 l,754,469

UNITED STATES 'PATENT OFFICE AUGUST KADOW, OIE' TOLEDO, OHIO, ASSIGNOR OF ONE-HALF TO WILBER- OWEN AND CHARLES W. OWEN, BOTH OF TOLEDO, OHIO ii-ILLING mom) Application filed June 19, 1926. Serial No. 117,018.

My invention relates to filling molds, and Fig. 1 of a somewhat modified form of apmore particularly to a. method and apparatus paratus, and Fig. 7 is a similar view showing whereby molds may be filled with such maanother modification. terial as molten metal without forming cavi- In the apparatus shown in Fig. 1, there is ties in the resultant casting. a mold consisting of mold halves 10 and 11. 55

More particularly, my invention relates to The mold is closed by handles 12, but one of filling molds b evacuating the as therewhich is shown, pivoted at 13 upon mold half from and intro ucing molten meta under at- 11, and adapted to close against pin 14 on mospheric pressure. mold half 10. In the construction shown,

10 I have found that, when molds are filled there is an adjustin screw 15 adapted to eo with-molten metal by means of a substantially cause exact closure o the mold. uniform vacuum sufliciently high to cause The mold halves have ground faces which complete filling of the mold, there are apt to form substantially air tight connection. At be cavities in the resultant casting. This is the bottom of the mold there is an'inlet 16 15 particularly true Where the casting is of conthrough which molten metal may be drawn 65 siderable size, or has portions which are of into the mold cavity 17. Vacuum ooves 18 considerable length in proportion to their surround the mold cavity. The a ce 19 of cross-section. I have discovered that these the mold between the mold cavity' and the cavities are not formed in the castin s when vacuum grooves is preferably ground slight- 20 a comparatively low vacuum is used, ut that ly so as to form an extremely thin passage 70 a sufliciently low vacuum to avoid the formabetween the mold 'cavity and the vacuum tion of cavities in the casting will not comgrooves. pletely fill the mold where the mold cavity is Vacuum grooves 18 lead into a recess 20 in of considerable height, especially where it has the upper end of the mold. A pipe 21, leadportions comparatively long in proportion to ing from recess 20, is provided with a quick- 75 their cross-section. Operating valve 22. Valve 22 is connected In my application Serial No. 94,716, filed by flexible pipe 23 with a needle valve 2A. March 15th, 1926, I have disclosed and Preferably, needle valve 24 is provided with claimed a way of overcoming these ditficulties a dial movable adjacent a pointer 25, so that by the shape of the intake opening of the the exact setting of the valve may be obso mold. By my present invention I avoid these served. Valve 24 controls the connection bedifliculties and completely fill the mold cavity tween pipe 23 and a casing 26, of any desired without formingcavities in the resultant castsize. Casing 26 may7 be connected, as by ing by using low vacuum upon the start and means of a pipe 27, with a suitable pump.

increasing the vacuum while the mold is be- The operation of the apparatus thus far ing filled, so that a sufiiciently high vacuum described is as follows: is formed towards the end of the filling period N eedle valve 24 is se t at a proper opening to completely fill the mold. Further details in a manner Which will be described later. of the invention will appear as the descrip- The opening through needle valve 24 is com- 40 tion proceeds. paratively small as compared with the open- In the accompanying drawings forming a ingav through valve 22. Then valve 22 is part of this specification, Figure 1 is a someopened, and immediately thereafter the lower what diagrammatic elevation of apparatus end of the mold is dipped m molten metal. adapted to carry out m method; Fig. 2 is After the mold is filled, valve 22 is closed,

45 an elevation of the insidye of one-half of the and the mold is raised and o ened. Theremold shown in Fig. 1; Fig. 3 is an enlarged after the casting is removed, t e mold closed, section on the line 3-3 of Figs. 1 and 2; Figs. and the operation repeated.

k4 and 5 are still greater enlargements upon When valve 22 is open, air rushes in and the same line as Fi 3, and showing castings fills the entire length of pipe 23. \This pipe 50 in the mold; Fig. 6 is an elevation similar to may be of any desiredlength, but is preferably long enough to contain a considerable amount of air. When the lower end, of the mold is dip ed into the molten metal, forming a seal or the mold inlet, evacuation of pipe 23, pipe 21, the vacuum grooves and the mold cavity immediately begins. As soon as the vacuum in the mold cavity is suflicient to cause the metal to rise, it enters the mold through inlet 16. As the metal rises in the mold, the vacuum in the mold cavity aproaches more nearly to that in chamber 26, so that the final filling of the mold is due to comparatively high vacuum.

The particular mold shown is adapted to form a battery grid.

My method is particularly advantageous in casting such an article, as the passages of the mold are long in proportion to their crosssection and abound in Sharp angles. If a constant low vacuum is used to fill such a mold, the metal solidifies before it reaches the top of the mold, leaving that portion of the mold cavity empty, as indicated in Fig. 3. A similar result occurs if needle valve 24 is opened insufliciently.

If substantially constant high vacuum is used, the resultant casting has cavities or bubbles therein, as indicated in Fig. 5. Not only are the larger portions, such as side bars 30, defective because of bubbles 31, but even the smaller cross-bars 32 are likewise defective because of bubbles 33. A somewhat similar result occurs if needle valve 24 is opened too widely.

If needle valve 24 is properly adjusted, vacuum is built up at such a rate that the mold cavity is completely filled, as indicated in Fig. 4, without the formation of cavities in the casting. Not only the side bars 28 of the grid are completely formed, but each of the small cross-bars 29 is likewise perfectly formed, as indicated in Fig. 4. p

Needle valve 24 must be adjusted to give a sufliciently low vacuum on the start to avoi the formation of cavities or bubbles in the casting, while it must be open sufliciently wide to build up the vacuum enough to completely fill the mold. The amount that the valve mustbe opened varies with the kind of metal, the shape and size of the mold cavity the temperature of the mold, the degree of vacuum in chest 26, the length and size of pipe 23 and of the vacuum grooves in the mold, and other varying factors. But when the needle valve is set so that a perfect casting results, it may be left unchanged so long as conditions remain constant. When changing conditions render it necessary, the needle valve may be adjusted.l Usually there is a suflicient margin of safety, between the point where the mold will be completely filled and .the point where imperfect castings will be formed, so that the needle valve needs adjustnient but seldom.

Valve 22 could be omitted, if desired, but

in that case there would be a constant entrance of air through valve 24, except When the mold was sealed by the metal. VVhcn valve 22 is used, vacuum is applied only when necessary.

As indicated above,,the amount Which valve 24 must be opened varies with the length and capacity of pipe 23. If more air is contained in the pipe, the valve must be opened wider to produce the same degree of vacuum in the same length of time.

In the modification shown in Fig. 6, this principle is taken advantage of to obtain accurate adjustment of the desired degree of vacuum. In this modiication, a cylindrical air receptacle 34 is interposed between valves 22 and 24. This acts as a reservoir for the air, and increases the amount which valve 24 must be opened to produce a given speed in building up the vacuum during the mold filling operation. Of course, the wider the valve must be opened to produce a given effect, the more it has to be turned in order to materially vary the rate at which the vacuum is built up. Consequently a finer adjustment can be made with a chamber interposed between the regulating Valve and the mold than can be obtained with the valve in close proximity to the mold.

In the construction shown, there is a piston 35 within cylinder 34, the piston having a stem 36 movable, by means of thumb screw 37 resting on bracket 38, to adj ust the piston as desired. It Will be apparent that raising the piston in cylinder 34 decreases the amount of air which must be Withdrawn to produce a given degree of vacuum, and, therefore, in-v creases the rapidity with which the vacuum is built up in the mold during the filling operation. On the other hand, lowering the piston lessens the rate at which vacuum is built up in the mold. In this way, an even finer adjustment may be obtained than by control of the needle valve.

It will be readily understood that, while the introduction of an air chamber between the regulating valve and the mold increases the accuracy with which adjustment may be made, it also increases the amount of air which must be evacuated to"produce a given effect in the mold, and, therefore, an air chamber is desirable only when necessary to secure the desired adjustment. The need of s'uch an interposed air chamber will 'depend upon the metal being molded, the shape o the castng being formed, and other conditions affecting the necessity of accurate adjustment'of the rate of increasin vacuum. Needle valve 24 is capable of ma ing sufliciently fine adjustment for ordinary operations, Without the interposition of any ai cavity greater than that incident to the use of the connecting pipe 23.

In Fig. 7 another modified form of apparatus is shown. In this view, a cylinder 40 is connected to the vacuum cavity within mold half 11a by means of a pipe 212. Within cylinder there is a piston 41 having a piston rod 42 actuated by a roller 43 running in a' cam groove 44 on a cam disc 45 mounted on a shaft 46. 4

In the operation of this device, metal is drawn into the mold by moving piston 41 to the left, as viewed in Fig. 7, and thus evacuating the mold. It will be readily understood that the degree of vacuum in the mold at any given portion of the operation is dependent upon the rapidity of the movement of piston 41, which in turn is dependent upon the speed of movement of the cam shaft and the shape of the cam grove. The apparatus shown in F ig. 7 is particularly adapted for the making of a great number of castings under constant conditions. Under such circumstances the necessary speed of movement of the piston at different portions of its travel maybe ascertained and then apparatus prepared to give it the proper movement.l Of course, different cams could be used for different articles, but, Where frequent adjustments are necessary, they can be made more easily by controlling the opening of a valve than by controlling the speed of movement of a pist-on.

Further modifications and combinations for efl'ecting substantially the same result in controlling'the degree of vacuum within the mold will readily appear to those skilled in the art. For example, an adjustable valve might be interposed between a pump. similar to that shown in Fig. 7, and the mold. The preferred method is to interpose an adjustable valve between a substantially constant source of vacuum and the mold, and regulate the valve in accordance With requirements.

While I have mentioned molten metal as the material to be cast, it Will be understood that the method is applicable where the mold is filled with other materials requiring like treatment.

Under some circumstances, the metal might be forced into' the mold under pressure. the

i pressure increasing during the filling of the mold. For example, pressure upon the metal might be exerted by gas, and the 'pressure of the gas might be built up through a regulatable valve, in a manner similar to that described above for increasing the vacuum within the mold cavity. Pressure and vacuum .might be used together, and various other similar combinations, obvious to those Skilled in the art, may be made, Within the scope of the appended claims.

What I claim is:

1. The method of introducing material into a mold by differential pressures upon the material outside the mold and inside the mold, the mold having a cavity of such shape and size that a constant differential pressure suflicient to fill the mold results in cavities Within the casting, which consists' in lgradually increasing' the dilferentiallpressure as ,the mold fills up.

2. The method of introducing material into a mold by differential pressures upon the material outside the mold and inside the mold, the mold having a cavity of such shape and size that a constant differential pressure sufficient to fill the mold results in cavities within the casting, which consists in maintaining a differential pressure during the initial filling of the mold low enough to avoid cavities in the casting, and increasing the differential pressure as the mold fills sufliciently to insure-complete fillin of the mold.

3. The method o introducing material into a mold, which consists in connecting the mold cavity With a source of material, subjecting the material outside the mold to a greater gaseous pressure than that within the mold2 and materially increasing the difference in said pressures between the time when the material starts to enter the mold and the time when the mold cavity is filled.

. 4. The method of introducing material into a mold having a cavit of such shape and size that filling the mold by a substantially constant difference in pressure upon the filling material outside of the mold and inside of the mold results in cavities in the casting, Which consists in connecting the lmold cavity With a source of material, subjecting the material outside the moldto a greater gaseous pressure than that within the mold, and governing the difference in said pressures so that the initial filling is at a sufliciently low differential pressure to' avoid cavitiesin the casting and the final filling is at a sufliciently high differential pressure to insure complete filling of the mold.

5. The method of filling a mold, which consists in connecting the mold-inlet with' material to be molded and thereafter reducing the. gas pressure within the mold progressively while the material is filling the mold cavity. I

6. The method of filling a mold, Which consists in connecting the mold inlet with material to be cast, thereafter exhausting air gradually from the mold, and governing the rate of exhaustion so that the mold cavity is completely filled without forming cavities in the casting.

7. The method of fillin a mold, which consistsin forming a seal etween the mold cavity and a source of material while the cavity is filled With air at substantially atmospheric pressure, and then gradually exhausting the air from the mold at such a rate that the final filling is under a materially higher vacuum than the initial filling.

8. The method of filling a mold, which consists in connecting the inlet of the mold cavity with a source of material While the cavity is filled With air at substantially at- 4 v lya-1,469

mospheric pressure, and exhausting the air from the cavity at a substantially constant rate so adjusted that the degree of vacuum within the mold cavity will materially increase during'the time in which it takes the material to till the mold.

9. The method of filling a mold, which consists in providing an air reservoir in connection with a 'mold cavity, connecting the mold cavity with a source of material while the air in the cavity and reservoir is at substantially atmospheric pressure, and thereafter exhausting'the air from said reservoir and cavlity at a predetermined rate. v 10. The method of filling va mold, which consists in providing an air reservoir in con- Inection with a mold cavity, connecting the mold cavity with a source of material whileV the air in the cavity and reservoir is at substantifally atmospheric pressure, and thereafter exhausting the air from said reservoir and cavity at a predetermined rate, and adjusting the size of the cavity so that the initial filling of the moldwill be at so low a vacuum that cavities are not formed in the Casting, and that the final filling will be unvder a sufiiciently high vacuuni to completely till the mold cavity.

11. In apparatus lof the character deqscribed, a mold, means for causing differential pressure on material outside of the mold and inside of the mold, said means being constructed to ygradually and materially in- .creafse said differential pressure during the Zl time it takesto fill the mold.

12. In ap'paratus of1 the character described, "a mold having a cavity therein, means for evacuating a1r from'said cavity, and means for adjusting the4 rate of evacu- 40 ation so that the degree of vacuum within the mold will increase materially during the time which it takes to fill the mold.

v13, In: -apparatus of the character described, a mold having amold cavity, a substantially uniform source of vacuum, connecting means having therein a passageway between said source of vacuumV and the mold, an adjustable valve controlling said passageway7 adjacent said source of vacuum, and a quick-opening valve controlling said passageway adjacent the mold.

14. In apparatus of the character de? scribed, a mold having a mold cavity, a substantially constant source of vacuum, connecting means having therein a passageway between said source of vacuum and the mold, an air reservoir interposed in said passageway, and means for 'adjusting the capacity of said reservoir. e

In testimony Whereof, I have hereunto signed my name to this specification.

AUGST KADOW. 

